main.go

package main

import (
	"net/http"
	"net/http/httptest"
	"net/http/httputil"
	"net/url"
)

func main() {
	url, err := url.Parse("https://google.com")
	if err != nil {
		panic(err)
	}
	http.Print()
	httptest.NewServer(httputil.NewSingleHostReverseProxy(url))
}

shell

$ export GO15VENDOREXPERIMENT=1
$ go version
go version go1.5rc1 linux/amd64
$ ls
main.go  vendor
$ ls vendor/net/http
http.go
$ go run *.go
testing

vendor-net-http-http.go

package http

func Print() {
	println("testing")
}